The practice of forming an iron group metal parts and components by compaction of powder and sintering at high temperatures in the solid state has long been known in the art. The greatest portion of such parts and components are made from iron powder, which is typically sintered in the temperature range of about 1000.degree. C. to about 1200.degree..
It has long been know that the sintering mechanism can be enhanced and can occur with equal effect at lower temperatures if a liquid metal phase is present during the sintering operation. In powder metallurgy, such liquid phases are generally restricted to copper, and certain copper alloys, for example, copper phosphide, added in quantities of about one or two percent by weight. Such additives do little or nothing to improve the intrinsic properties of the iron, but do permit higher strengths and higher densities to be achieved at lower sintering temperatures, and therefore a cost saving in parts requiring good physical properties. While copper alone only marginally reduces sintering temperatures (to about 1100.degree. C.), copper alloys, which further reduce the temperature, for example, to about 970.degree. C. for copper phosphide, are relatively expensive and less effective in property improvement.
It would be desirable to develop alloys which would have excellent wetting qualities on ferrous metal surfaces, and which add elements to the powder compact which improve strength and in some cases corrosion resistance and which are possible of lower cost than the copper alloys.
U.S. Pat. No. 3,689,257 pertains to the use of a Fe-Si sintering additive for use with higher melting point materials to produce an alloy which is a solid solution of all elements. The materials produced by the techniques described in that patent do not have two distinct phases.
U.S. Pat. No. 4,011,051 pertains to wear resistant alloy composites, however, it does not disclose a compact having iron as a discontinuous phase.
U.S. Pat. Nos. 4,283,225, 4,402,742 and 4,410,604 cited in the parent application pertain to various iron based brazing alloys and not to the compacts of this invention containing the recited phases.
U.S. Pat. No. 4,504,312 also pertains to a wear resistant alloy and does not disclose a material having the recited phases of this invention. The sintering is carried on for a sufficient time to form as alloy rather than a composite having distinct phases.